Overview

Brief Summary

The family Pomacanthidae (angelfishes) is distinguished from similar families by the presence of one or more prominent spines at the angle of the preopercle (the forward, bony part of the gill cover normally separated by a groove from the rear portion). Angelfishes have a single, continuous dorsal fin; some species have filamentous extensions of one or more dorsal rays. Most angelfishes are brightly colored and several species are found in the aquarium trade. Juveniles of the genus Pomacanthus often have strikingly different color patterns than adults of the same species.

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Physical Description

Diagnostic Description

Description

Tropical Atlantic, Indian, and (mainly western) Pacific. Strongly compressed body. Angle of preopercle with a strong spine. Three spines in anal fin. Many species have an elongate extension on hind margin of soft dorsal and anal fins. Caudal fin rounded to strongly lunate with 15 branched rays. Vertebrae 24 (10+14). Striking coloration, markedly different between juveniles and adults of many species. In shallow waters of less than 20 m deep, very seldom below 50 m; generally near coral reefs. All species studied to date are protogynous hermaphrodites with 'haremic' social system. Species of Centropyge feed primarily on filamentous algae and species of Genicanthus feed primarily on zooplankton; most others feed on sponges, invertebrates, algae and fish eggs. Poma- = operculum, acanth- (gr.) = spine

Contents

With their bright colours and deep, laterally compressed bodies, marine angelfishes are some of the more conspicuous residents of the reef. They most closely resemble the butterflyfishes, a related family of similarly showy reef fish. Marine angelfish are distinguished from butterflyfish by the presence of strong preopercle spines (part of the gill covers) in the former. This feature also explains the family name Pomacanthidae; from the Greek πομα, poma meaning "cover" and ακάνθα, akantha meaning "thorn".

Many species of marine angelfishes have streamer-like extensions of the soft dorsal and anal fins. The fish have small mouths, relatively large pectoral fins and rounded to lunate tail fins. The largest species, the gray angelfish, Pomacanthus arcuatus, may reach a length of 60 cm (24 in); at the other extreme, members of the genus Centropyge do not exceed 15 cm (5.9 in). A length of 20 to 30 cm (7.9 to 11.8 in) is average for the rest of the family. The smaller species are popular amongst aquarists, whereas the largest species are occasionally sought as a food fish; however, there have been reports of ciguatera poisoning as a result of eating marine angelfish.

The Queen angelfish, grows to be 45 cm (18 in). With neon blue and yellow scales, with iridescent purple and orange markings, surprisingly it is not conspicuous, and actually hides very well, and is very shy.

The larger species are also quite bold and seemingly fearless; they are known to approach divers. While the majority adapt easily to captive life, some are specialist feeders which are difficult to maintain. Feeding habits can be strictly defined through genus, with Genicanthus species feeding on zooplankton and Centropyge preferring filamentous algae. Other species focus on sessile benthicinvertebrates; sponges, tunicates, bryozoans, and hydroids are staples.

Most marine angelfishes restrict themselves to the shallows of the reef, seldom venturing deeper than 50 m (160 ft). The recently described Centropyge abei is known to inhabit depths of 150 m (490 ft). They are diurnal animals, hiding amongst the nooks and crevices of the reef by night. Some species are solitary in nature and form highly territorial mated pairs; others form harems with a single male dominant over several females. As juveniles, some species may eke out a living as cleaner fish.

Common to many species is a dramatic shift in coloration associated with maturity. For example, young male ornate angelfish, Genicanthus bellus, have broad, black bands and are indistinguishable from females; as they mature, bright orange bands develop on the flanks and back. Thought to correspond to social rank, these colour shifts are not necessarily confined to males; all marine angelfish species are known to be protogynous hermaphrodites. This means that if the dominant male of a harem is removed, a female will turn into a functional male.

As pelagic spawners, marine angelfishes release many tiny buoyant eggs into the water which then become part of the plankton. The eggs float freely with the currents until hatching, a high number falling victim to planktonic feeders.